1. Technical Field
The present disclosure relates to a transmission line, and more particularly to a transmission line with a structure which is capable of forming a passive equalizer, and the electrical apparatus using the same.
2. Description of Related Art
To continuously integrate several commercial electrical products and improve the performance of the integrated electrical apparatus, the issue for increasing the speed of the signal transmission between chips becomes important to the electrical product manufacturers. In the different signal transmission mediums, the differential signal lines have the low crosstalk and electromagnetic radiation, therefore widely being applied to the high speed signal transmission. However, when the practical circuit layout is considered, the layout of the differential signal lines are usually designed to match the other circuit, such that the ideal layout of the differential signal lines is forced to be affected by the non-continuous structure. Hence, the common mode noise is generated, and the transmission quality of the differential mode signal is decreased.
When the common mode noise is excited and propagated in the printed circuit board, the common mode noise tends to radiate through the analogous antenna structure of the printed circuit board, such that the ElectroMagnetic Interference (EMI) is generated to affect the differential mode signal transmitted in the differential signal lines. The differential mode signal may further affected by the non-ideal characteristics of the structure or/and the material of the differential signal lines (such as the attenuation of the medium or the metal), and thus the transmission quality of the differential mode signal is decreased. The various effects mentioned above may severely decrease the quality of the eye pattern at the receiving end of the differential signal lines, and further cause the erroneous logic decision when the back-end chip reads the differential signal.
Currently, several methods are provided to suppress the common mode noise and improve the eye patter of the differential mode signal. For example, the designs of the transmission line implemented by the common mode choke coil, the low temperature cofired ceramics common mode filter, and the slotted ground plane filter are proposed, and that the designs are capable of suppressing the common mode noise is proofed. In addition, the transmission line being designed to incorporate with the active equalizer is proposed, and the transmission line has the better performance. However, the active equalizer needs the extra power consumption and chip area, and therefore the manufacturing cost of the transmission line is increased, and the manufactured electrical apparatus adopting the transmission line cannot have the low power consumption and the slim and thin dimension.